Abstract: OBJECTIVE To study the influence of Tanreqing injection on biofilm formation of Pseudomonas aeruginosa so as to offer new treatment approaches for infections. METHODS From Aug 2015 to Sep 2015, the standard bacterial strain ATCC27853 provided by the bacteriology room of the First Affiliated Hospital of Baotou Medical College was adopted, and the minimum inhibitory concentration (MIC) of Tanreqing injection to the P.aeruginosa was determined by using 96 hole culture plate and micro dilution method, the SMIC of Tanreqing injection to the biofilm of P.aeruginosa was determined by means of MTT assay, and the influence of drugs on the biofilm was observed with the use of scanning electron microscope (SEM). RESULTS The MIC of the Tanreqing injection to the P.aeruginosa was 100 μg/ml, and the antibacterial activity was decreased with the reduction of concentration of the Tanreqing injection. The SEM observation revealed that the Tanreqing injection showed significant inhibitory effect on biofilm formation of the P.aeruginosa. CONCLUSION The Tanreqing injection can effectively inhibit the formation of biofilm of the P.aeruginosa.